Somatic cancer mutations in the DNMT2 tRNA methyltransferase alter its catalytic properties

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Transfer RNA (tRNA) methylation is a critical post-transcriptional modification.
• Aberrations in tRNA modification are linked to cancer development.
• The DNMT2 enzyme methylates C38 of tRNA-Asp and is implicated in cellular physiology and stress response, with altered expression in cancer tissues.

Purpose of the Study:

• To investigate the impact of DNMT2 somatic mutations found in cancer tissues on enzyme activity.
• To determine if these mutations affect the methylation of tRNA-Asp.

Main Methods:

• Generation and purification of 13 DNMT2 variants.
• Assessment of protein folding using circular dichroism spectroscopy.
• In vitro testing of RNA methylation activity on tRNA-Asp.

Main Results:

• One mutation (E63K) resulted in a twofold increase in DNMT2 activity.
• Two mutations (G155S, L257V) caused a significant decrease (over fourfold) in activity.
• Two mutations (R371H, G155V) rendered the DNMT2 protein nearly inactive.

Conclusions:

• Somatic mutations in DNMT2 can profoundly alter its enzymatic activity.
• These activity changes suggest a functional role for DNMT2 mutations in tumorigenesis.
• Further research is warranted to elucidate the precise mechanisms by which these mutations contribute to cancer.